In general, portable wireless terminals are classified into bar-type terminals, flip-type terminals, and folder-type terminals according to their appearance. Recently, the folder-type terminals have prevailed in the wireless terminal market, because it is easy to make them in a compact size with reduced weight. In addition, body-wearable type terminals and sliding-type terminals have appeared, in order to satisfy the diversified taste or desires of customers.
FIG. 1 is an exploded perspective view showing an embodiment of a driving apparatus of a sliding-type portable wireless terminal 100 according to the prior art. As shown in FIG. 1, the sliding-type portable wireless terminal 100 has a main body 101, a sub-body 102, and a spring module 150 which acts as a driving apparatus and which couples them in such a manner that they can slide relative to each other.
The sub-body 102 has a pair of sliding guides 127 positioned on its rear surface for smooth sliding. The sliding guides 127 preferably have the shape of an H-beam having lateral grooves (not shown), so that the sub-body 102 can slide in a stable manner and can be prevented from escaping from the main body 101. The sliding guides 127 are retained in coupling grooves 123, which are formed on the rear surface of the sub-body 102 along its longitudinal direction.
The spring module 150 has a rear cover 151, a front cover 153, and torsion springs 155.
The rear cover 151 is retained on the front surface of the main body 101. The rear cover 151 is positioned on the upper portion of the front surface of the main body 101 and a key pad (not shown) is positioned on the lower portion thereof.
The front cover 153 has sliding grooves 153d formed along its longitudinal direction, which corresponds to the sliding guides 127, and guide slits 153c formed along the longitudinal direction, which penetrates both the sliding grooves 153d and the interior of the front cover 153. The sliding grooves 153d are engaged with the lateral grooves of the sliding guides 127 so that the spring module 150 can slide on the slide guides 127. The upper surfaces of the sliding guides 127 are in communication with the interior of the front cover 153 via the guide slits 153c. The front cover 153 also has support holes 153f formed thereon for supporting the torsion springs 155. After being retained on the rear cover 151 and being coupled to the sliding guides 127 on the rear surface of the sub-body 102, the front cover 153 acts as a bridge which connects the main body 101 and the sub-body 102 to each other in such a manner that they can slide relative to each other.
Each torsion spring 155 has a coil 155a, a first retaining end 155b extending from an end of the coil 155a, and a second retaining end 155c extending from the other end of the coil 155a. The coils 155a of the torsion springs 155 are moved along a predetermined path within the rear cover 151. The first retaining ends 151b protrude to the exterior via the guide slits 153c of the front cover 153 and are retained on the sliding guides 127, which are positioned on the rear surface of the sub-body 102. The second retaining ends 155c are retained in the support holes 153f of the front cover 153. The torsion springs 155 accumulate an elastic force, which acts in such a direction that the first and second retaining ends 155b and 155c move away from each other. The elastic force enables the spring module 150 to provide a driving force which causes the sub-body 102 to slide on the main body 101.
However, such a sliding-type portable wireless terminal according to the prior art has a problem in that it generates a noise during opening/closing and the service life of the product is shortened by the friction among components because of the structure, which uses a spring module to generate a driving force. In particular, as the coil springs in the spring module are moved, they generate a noise and cause friction among components, which wears the components and shortens the service life of the product.